1. Field of the Invention
The present invention relates to an oil pan of an internal combustion engine.
2. Description of the Related Art
Oil for lubricating respective sliding portions of an internal combustion engine is deposited in the oil pan of the internal combustion engine and supplied to those respective sliding portions of the internal combustion engine by means of an oil pump and the like through an oil strainer.
After lubricating a sliding surface between a cylinder and a piston and bearings of a connecting rod and crank shaft of the sliding portions of the internal combustion engine, oil floats in the condition of mist within a crank case. The oil is heated by a high-temperature blow-by gas leaking from the sliding surface between the cylinder and the piston, drops onto a baffle plate, and thereafter returns to the oil pan.
As regards the internal combustion engine, for example, Japanese Utility Model Application Laid-Open NO.HEI4-71716 discloses a structure for preventing the oil strainer from being exposed over the oil surface and sucking air due to the tilt of the oil surface generated at the time of acceleration or deceleration for startup or stop of a vehicle or turning. Therefore, the oil is stably supplied to the respective sliding portions of the internal combustion engine, thereby improving wear resistance.
According to the structure disclosed in this document, a lidded cylindrical baffle plate for defining an oil holding space to surround the oil strainer is provided on an oil sump within the oil pan. This lidded cylindrical baffle plate has a communicating opening hole which communicates with the interior of the oil pan. The oil strainer is inserted into the communicating opening at its lid portion. A dent portion which communicates with the interior of the oil pan is formed at the bottom of this cylindrical body. Consequently, by holding a sufficient amount of oil within the oil holding space by this cylindrical body, oil can be supplied to the respective sliding portions of the internal combustion engine stably even when the oil surface is tilted.
However, the structure of such oil pan allows hot oil recovered after floating within the crank case to enter into the oil holding space through the communicating opening hole formed in the lid portion on the top of the baffle plate. Consequently, the hot oil is supplied to the respective sliding portions of the internal combustion engine from the oil strainer, thereby possibly badly affecting the lubrication performance.